Laravel 5 Middlewere, using AuthorizesRequests trait but adding a custom message based on action (index, show, destroy etc)

middlware.php

<?php

namespace App\Http\Middleware\Admin;

use Closure;
use Illuminate\Contracts\Auth\Access\Gate;
use Illuminate\Foundation\Auth\Access\AuthorizesRequests;

use App\Models\Site as Model;

class Site
{
	use AuthorizesRequests;

	/**
	 * Key for translations.
	 * 
	 * @var	string
	 */
	public $key = 'site';

	/**
	 * Handle an incoming request.
	 *
	 * @param  \Illuminate\Http\Request  $request
	 * @param  \Closure  $next
	 * @return mixed
	 */
	public function handle($request, Closure $next)
	{
		$this->authorize(last(explode('.', $request->route()->getName())), $request->site ?: new Model);

		return $next($request);
	}

    /**
     * Authorize the request at the given gate.
     *
     * @param  \Illuminate\Contracts\Auth\Access\Gate  $gate
     * @param  mixed  $ability
     * @param  mixed|array  $arguments
     * @return \Illuminate\Auth\Access\Response
     *
     * @throws \Symfony\Component\HttpKernel\Exception\HttpException
     */
    public function authorizeAtGate(Gate $gate, $ability, $arguments)
    {
		 try {
			if($gate->check($ability, $arguments) === false) {
				throw new \Illuminate\Auth\Access\UnauthorizedException(trans($this->key . '.' . $ability));
			}
			return Response();
        } catch (UnauthorizedException $e) {
            throw $this->createGateUnauthorizedException(
                $ability, $arguments, $e->getMessage(), $e
            );
        }
    }

}